1. Field of the Invention
The present invention relates to the field of thermal oxidation burners.
2. Description of the Prior Art
The disposing of certain types of materials by means of burning or incineration has developed into a necessary aspect of waste management. While most waste was simply placed into the earth, this practice has proved to be detrimental to the environment. Pooled waste products often formed toxic byproducts and/or surfaced undesirably above ground at a later date. While solid compositions are routinely disposed of, their decomposition, either naturally or through a waste processing system, often creates other undesirable byproducts that themselves require subsequent management or treatment. One category of byproduct compositions requiring alternative waste management techniques are Volatile Organic Compounds, (VOCs).
Volatile Organic Compounds are organic chemical compounds that have vapour pressures under normal conditions high enough to significantly vaporize and enter the atmosphere. A wide range of carbon-based molecules, such as aldehydes, ketones, and hydrocarbons are VOC's. Common artificial sources of VOCs include petroleum byproducts, paint thinners, and dry cleaning solvents. Additionally, VOCs may be generated in the context of the disposal of carbon based materials or products such as used tires.
VOCs can be undesirable when released into the environment where they can become soil and groundwater contaminants. Also, VOCs escaping into the air contribute to air pollution. For example, methane is one greenhouse gas which may contribute to enhanced global warming. Other VOCs such as benzene are suspected to contribute to cancer through prolonged exposure and are toxic when inhaled. Other VOCs react with nitrogen oxides in the air in the presence of sunlight to form ozone. Ozone is known to pose a health threat by causing respiratory problems and high concentrations of low level atmospheric ozone can damage crops.
In response to the need for effectively disposing of VOCs before they escape into the atmosphere, waste managers turned to the art of thermal oxidation to break down material into manageable compounds or be converted into heat energy. Thermal oxidation is a method of pollution control that can be applied to incineration for air polluted with small particles or combustible solids or liquids. By thermally oxidizing material such as VOCs, molecular bonds break free of each other and reform into inert or useful by products. Often, the efficiency of decomposing VOCs will depend on the efficiency of the flame burning the material. Efficiency in burning depends largely on the temperature of the flame, the turbulence of the system which determines how much fluid movement exists for oxidizing VOCs, and the retention time in exposing material to the flame.
Until now, the prior art in thermal oxidation depended largely on using a singular flame source or singular ring of flames. However, these prior burner designs suffer from various inefficiencies. The VOCs passing through the burner receive limited exposure to the actual flame or combustion area thus not permitting sufficient flame contact for complete burning. The VOCs also do not effectively mix with the ambient oxygen to oxidize effectively for a clean burn. What occurs is relatively “dirty” burning where a significant amount of underburned VOCs remain present.
Other efforts to improve the thermal oxidation of VOCs have focused on increasing the flame temperature itself. Typical flame temperatures in the prior art range between 1000° F. to 1800° F. While effective in one sense, such a strategy suffers from mechanical drawbacks when using a singular flame source. Certain VOCs require more than just increased temperature to effectively decompose. Without the proper oxidizing mix, the VOCs will ineffectively break apart and reform into similar molecules or worse, escape back into the atmosphere. These prior efforts produced partially combusted compounds that were still harmful to the environment. Also, using fuel sources sufficient to increase the flame temperature to a more effective level and render the process economically unviable.
Thus a need exists in the marketplace for an improved burner capable of efficiently decomposing compounds. Aspects of the present invention fulfill this need.